Dr. Rick Fletcher Homework 4 Chemistry 101 May 8, 2009 There is one most correct response to each of the multiple choice questions. Choose the best answer. Each of the twenty-five questions is worth 1 point. Please work through the entire exam and circle the best answer on this exam paper. Bring this completed exam into class on Friday and transfer the responses to the Scantron sheet all at one time. We will do this at the beginning of class period on Friday, May 8. Keep this completed exam and use it to check your answers on the key that will be posted online after class on Friday. 2.54 cm = 1 in 454 g = 1 lb 946 ml = 1 qt 5280 ft = 1 mile 16 oz = 1 lb 4 qt = 1 gal heat = (sp. Ht.) X (mass) X (ΔTemp) T (K) = T ( C) + 273.15 T( F) = (1.8 X T( C)) + 32 1 cal = 4.184 J
1. Select the strong acid from the following list. A. H 2 SO 4 (aq) B. H 3 PO 4 (aq) C. H 2 S(aq) D. CH 3 CO 2 H(aq) E. HF(aq) 2. Given an OH - concentration of 1.0 10-4 M, calculate the H 3 O + concentration, then identify the solution as acidic, basic, or neutral. A. [H 3 O + ] = 1.0 10-4, basic B. [H 3 O + ] = 1.0 10-4, acidic C. [H 3 O + ] = 1.0 10-10, acidic D. [H 3 O + ] = 1.0 10-10, basic E. [H 3 O + ] = 1.0 10-7, neutral 3. Calculate the ph of a solution that has [H 3 O + ] = 3.1 10-8 M. A. ph = 6.49 B. ph = 8.00 C. ph = 7.51 D. ph = 3.18 E. ph = 3.10 4. How much water must be added to 500.0 ml of a 3.00 M HCl solution to obtain a solution that is 2.00 M? A. 1.00 L B. 7.50 10 2 ml C. 2.50 10 2 ml D. 12.0 L E. 1.50 L 5. A solution contains 22.0 g of HCl dissolved in sufficient water to give a total mass of 125.0 g. What is the molality of the solution? A. 4.83 m B. 2.75 m C. 5.86 m D. 0.250 m E. 0.176 m
6. Select the solution below that is the most basic. A. [H 3 O + ] = 1.0 10-8 M B. [H 3 O + ] = 1.0 10-7 M C. [H 3 O + ] = 1.0 10-4 M D. [H 3 O + ] = 1.0 10-6 M E. [H 3 O + ] = 1.0 10-10 M 7. Which of the following statements regarding the rule "like dissolves like" is incorrect? A. Potassium nitrate, KNO 3, is soluble in water. B. Since cooking oil is composed primarily of hydrocarbons, it is insoluble in water. C. Iodine, I 2, is very soluble in water. D. Ethanol, CH 3 CH 2 OH, is water-soluble. E. Cooking oil, a nonpolar substance, is soluble in hexane, C 6 H 14. 8. What volume of 3.00 M NaOH contains 1.75 mol NaOH? A. 1.71 L B. 0.583 L C. 3.00 L D. 4.75 L E. 1.75 L 9. Select the two Brønsted-Lowry acids in the equation: HCN(aq) + H 2 O(aq) CN - (aq) + H 3 O + (aq) A. H 3 O + and CN - B. HCN and CN - C. HCN and H 2 O D. HCN and H 3 O + E. H 2 O and CN - 10. If the ph of a blood sample is 7.60, what is the H 3 O + concentration in the blood? A. 7.6 M B. 2.5 10-7 M C. 2.5 10-9 M D. 2.5 10-8 M E. 6.4 M
11. Predict the molecular shape and give the approximate bond angles of the OF 2 molecule. A. trigonal planar, 120 o B. linear, 180 o C. trigonal pyramidal, 109.5 o D. bent, 109.5 o E. tetrahedral, 109.5 o 12. When phosphorus reacts with chlorine, phosphorus trichloride is formed according to the equation: P 4 (s) + Cl 2 (g) PCl 3 (l) (unbalanced) Balance the equation and determine how many grams of phosphorus would be required to form 75.0 g of phosphorus trichloride, assuming there is sufficient chlorine available. A. 16.9 g B. 333 g C. 67.8 g D. 135 g E. 271 g 13. The number of neutrons in an atom of copper-65 is: A. 65 B. 36 C. 84 D. insufficient information given E. 29 14. The symbol for the element barium is. A. Be B. Bi C. Ba D. B E. Br 15. Write the electron configuration for the element phosphorus. A. 1s 2 2s 8 3s 5 B. 1s 2 2s 2 2p 3 C. 1s 2 2s 2 2p 6 3s 5 D. 1s 2 2s 2 2p 6 3s 2 4p 3 E. 1s 2 2s 2 2p 6 3s 2 3p 3
16. Rank the following elements in order of increasing atomic size: F, P, Mg, Cs A. P < Mg < F < Cs B. Cs < F < Mg < P C. Cs < Mg < P < F D. F < P < Mg < Cs E. Cs < Mg < F < P 17. A 7.50 g sample of pyrite (FeS 2 ) contains 3.49 g of iron. What are the percents of iron and sulfur in pyrite (also known as "Fool's Gold" because of its golden color)? A. 46.5% Fe and 53.5% S B. 53.5% Fe and 46.5% S C. 33.3% Fe and 66.7% S D. 57.4% Fe and 42.6% S E. 66.7% Fe and 33.3% S 18. If 8.53 10 24 molecules of a substance have a mass of 483 g, what is the molar mass of the substance? A. 1.77 10 22 g/mol B. 34.1 g/mol C. 6.86 10 3 g/mol D. 0.0293 g/mol E. 4.12 10 27 g/mol 19. Calculate the molar mass of PH 3. A. 31.98 g/mol B. 33.99 g/mol C. 2.05 10 25 g/mol D. 34.00 amu E. 31.98 amu 20. When copper metal is placed in a solution of zinc nitrate, will a reaction occur? If so, what is the balanced equation for the reaction? A. Yes. Cu(s) + Zn(NO 3 ) 2 (aq) CuNO 3 (aq) + ZnNO 3 (aq) B. Yes. Cu(s) + Zn 2 NO 3 (aq) CuNO 3 (aq) + Zn(aq) C. No reaction will occur. D. Yes. Cu(s) + Zn 2 NO 3 (aq) CuNO 3 (aq) + 2Zn(aq) E. Yes. Cu(s) + Zn(NO 3 ) 2 (aq) Cu(NO 3 ) 2 (aq) + Zn(s)
21. Which of the following formula/name pairs is incorrect? A. LiNO 3 lithium nitrate B. MgCl 2 magnesium dichloride C. BaBr 2 barium bromide D. CuO copper(ii) oxide E. Sr(OH) 2 strontium hydroxide 22. What is the percent-by-mass concentration of NaCl in a solution that is prepared by adding 14.0 g of NaCl to 75.0 g of water? A. 15.7% B. 18.7% C. 61.0% D. 5.36% E. 24.0% 23. In the process of obtaining lead from PbS, or galena, the galena is "roasted" (heated in the presence of oxygen), so that the following reaction occurs: 2PbS(s) + 3O 2 (g) 2PbO(s) + 2SO 2 (g) If 50.0 g of PbS reacts with 25.0 g of oxygen, how many grams of PbO will be formed? A. 69.9 g B. 163 g C. 116 g D. 46.6 g E. 93.2 g 24. Nitrogen monoxide reacts with oxygen according to the reaction: 2NO(g) + O 2 (g) 2NO 2 (g) If 10 moles of nitrogen monoxide react with 4 moles of oxygen, how many moles of NO 2 will be formed? A. 4 moles B. 14 moles C. 8 moles D. 10 moles E. 12 moles
25. Rank the boiling points of the following compounds from lowest to highest: CO 2, LiF, H 2 O A. H 2 O < LiF < CO 2 B. H 2 O < CO 2 < LiF C. LiF < CO 2 < H 2 O D. CO 2 < H 2 O < LiF E. CO 2 < LiF < H 2 O